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    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <button id="btn">操作</button>
    <div id="box">div 标签</div>
    <input type="password">
    <script>
        var box = document.querySelector('div');
        var input = document.querySelector('input');
        var btn = document.querySelector('button');
        btn.onclick = function(){
            box.id = "content";
            input.type = "text";
        }

    </script>
</body>
</html>